| Message ID | 20211008100033.105538-1-krzysztof.kozlowski@canonical.com |
|---|---|
| Headers | show |
| Series | revert v4.17 stable backport patch | expand |
On 08/10/2021 11:00, Krzysztof Kozlowski wrote: > BugLink: https://bugs.launchpad.net/bugs/1946464 > > [Impact] > > Commit 5047ef5725ed ("x86/mm: Don't free P4D table when it is folded at runtime") should not be backported to v4.15 because: > 1. It adds pgtable_l5_enabled which does not exist in v4.15, > 2. It is marked as v4.17+ > 3. It is marked as fixing commit which does not exist in v4.15 and was not backported there. > > allyesconfig in x86_64 fails to build: > --- > In file included from ../arch/x86/include/asm/mmu_context.h:12, > from ../include/linux/mmu_context.h:5, > from ../arch/x86/kvm/../../../virt/kvm/async_pf.c:26: > ../arch/x86/include/asm/pgalloc.h: In function ‘p4d_free’: > ../arch/x86/include/asm/pgalloc.h:185:7: error: ‘pgtable_l5_enabled’ undeclared (first use in this function); did you mean ‘movable_node_enabled’? > 185 | if (!pgtable_l5_enabled) > | ^~~~~~~~~~~~~~~~~~ > | movable_node_enabled > > --- > > [Test Plan] > > Compile the x86_64 KVM code. > > [Where problems could occur] > > If backport commit is actually needed, e.g. when we backport 5-level page tables and commit 98219dda2ab5 ("x86/mm: Fold p4d page table layer at runtime"), this could cause double-free and memory corruption. > > When backporting x86_64 5-level pages, we need to bring this commit as well. > > Best regards, > Krzysztof > > Krzysztof Kozlowski (1): > UBUNTU: SAUCE: Revert "x86/mm: Don't free P4D table when it is folded > at runtime" > > arch/x86/include/asm/pgalloc.h | 3 --- > 1 file changed, 3 deletions(-) > Yep, makes perfect sense, thanks Krzysztof Acked-by: Colin Ian King <colin.king@canonical.com>
On 2021-10-08 12:00:32 , Krzysztof Kozlowski wrote: > BugLink: https://bugs.launchpad.net/bugs/1946464 > > [Impact] > > Commit 5047ef5725ed ("x86/mm: Don't free P4D table when it is folded at runtime") should not be backported to v4.15 because: > 1. It adds pgtable_l5_enabled which does not exist in v4.15, > 2. It is marked as v4.17+ > 3. It is marked as fixing commit which does not exist in v4.15 and was not backported there. > > allyesconfig in x86_64 fails to build: > --- > In file included from ../arch/x86/include/asm/mmu_context.h:12, > from ../include/linux/mmu_context.h:5, > from ../arch/x86/kvm/../../../virt/kvm/async_pf.c:26: > ../arch/x86/include/asm/pgalloc.h: In function ‘p4d_free’: > ../arch/x86/include/asm/pgalloc.h:185:7: error: ‘pgtable_l5_enabled’ undeclared (first use in this function); did you mean ‘movable_node_enabled’? > 185 | if (!pgtable_l5_enabled) > | ^~~~~~~~~~~~~~~~~~ > | movable_node_enabled > > --- > > [Test Plan] > > Compile the x86_64 KVM code. > > [Where problems could occur] > > If backport commit is actually needed, e.g. when we backport 5-level page tables and commit 98219dda2ab5 ("x86/mm: Fold p4d page table layer at runtime"), this could cause double-free and memory corruption. > > When backporting x86_64 5-level pages, we need to bring this commit as well. > > Best regards, > Krzysztof > > Krzysztof Kozlowski (1): > UBUNTU: SAUCE: Revert "x86/mm: Don't free P4D table when it is folded > at runtime" > > arch/x86/include/asm/pgalloc.h | 3 --- > 1 file changed, 3 deletions(-) > > -- > 2.30.2 > > > -- > kernel-team mailing list > kernel-team@lists.ubuntu.com > https://lists.ubuntu.com/mailman/listinfo/kernel-team
BugLink: https://bugs.launchpad.net/bugs/1946464 [Impact] Commit 5047ef5725ed ("x86/mm: Don't free P4D table when it is folded at runtime") should not be backported to v4.15 because: 1. It adds pgtable_l5_enabled which does not exist in v4.15, 2. It is marked as v4.17+ 3. It is marked as fixing commit which does not exist in v4.15 and was not backported there. allyesconfig in x86_64 fails to build: --- In file included from ../arch/x86/include/asm/mmu_context.h:12, from ../include/linux/mmu_context.h:5, from ../arch/x86/kvm/../../../virt/kvm/async_pf.c:26: ../arch/x86/include/asm/pgalloc.h: In function ‘p4d_free’: ../arch/x86/include/asm/pgalloc.h:185:7: error: ‘pgtable_l5_enabled’ undeclared (first use in this function); did you mean ‘movable_node_enabled’? 185 | if (!pgtable_l5_enabled) | ^~~~~~~~~~~~~~~~~~ | movable_node_enabled --- [Test Plan] Compile the x86_64 KVM code. [Where problems could occur] If backport commit is actually needed, e.g. when we backport 5-level page tables and commit 98219dda2ab5 ("x86/mm: Fold p4d page table layer at runtime"), this could cause double-free and memory corruption. When backporting x86_64 5-level pages, we need to bring this commit as well. Best regards, Krzysztof Krzysztof Kozlowski (1): UBUNTU: SAUCE: Revert "x86/mm: Don't free P4D table when it is folded at runtime" arch/x86/include/asm/pgalloc.h | 3 --- 1 file changed, 3 deletions(-)